Device and method for detecting non-writable region of optical recording medium
View Patent ↗Device and method for detecting a non-writable region of an optical recording medium, wherein a read channel 1 signal and a read channel 2 signal are sliced at respective slice levels to produce header mask signals, and a header region which is a non-writable region is determined for the header mask signal taking the slice levels and written/unwritten regions ion the disk, whereby permitting stabilization of servos because servo error signals, such as a tracking error signal, and a focus error signal can be held exactly at a header region even if the servos are not stable, that prevents deterioration of a data quality in writing and reading, and permitting to shift an optical pickup to a desired position and accurate measurement of an amount of eccentricity because there is no influence of the header in a track jump and a disk eccentricity measurement.
1. A method for detecting a non-writable region of an optical recording medium including a plurality of non-writable regions of different phases having information for controlling a writable data region between the writable data regions, the method comprising the steps of:
(1) detecting a sum of optical signals reflected at the optical recording medium;
(2) comparing the summed signal to a reference value; and
(3) determining if a current position is a writable region or a non-writable region based on the result of the comparison.
2. The method as claimed in claim 1 , wherein step (3) determines that the current position is a non-writable region if the summed signal is higher than the reference value.
3. The method as claimed in claim 1 , wherein the non-writable region is a header region.
4. The method as claimed in claim 1 , wherein step (1) includes a step of obtaining at least a bottom hold signal from the summed signal.
5. The method as claimed in claim 4 , wherein step (3) determines the present region as an non-writable region if the bottom held value is greater than a reference value, and as a writable region if the bottom held value is smaller than the reference value.
6. The method as claimed in claim 1 , further comprising holding a servo error signal for carrying out a servo control to read or write data if the current position is determined as a non-writable region.
7. The method as claimed in claim 1 , further comprising:
counting a number of the determined non-writable regions, to determine the present track of being a land track or a groove track, and
performing a land/groove switching operation depending on a result of the determination.
8. A method for detecting a non-writable region of an optical recording medium including a plurality of non-writable regions of different phases having information for controlling a writable data region between the writable data regions, the method comprising the steps of:
(1) detecting a read channel 1 signal being an added signal of optical signals reflected at the optical recording medium;
(2) comparing the read channel 1 signal to a reference value; and
(3) discriminating a writable region or a non-writable region based on a result of the comparison.
9. The method as claimed in claim 8 , wherein step (1) includes a step of detecting a read channel 2 signal being a difference signal of optical signals reflected from the optical recording medium.
10. The method as claimed in claim 9 , wherein step (2) compares the detected signal with a reference value, thereby to determine a region as the non-writable region based on a result of the comparison.
11. A method for detecting a non-writable region of an optical recording medium, the method comprising the steps of:
(1) detecting a read channel 2 signal being a difference of optical signals reflected from the optical recording medium, the optical recording medium includes a plurality of non-writable regions of different phases having information for controlling a writable data region between the writable data regions;
(2) comparing the detected signal with a reference value; and
(3) determining a region as the non-writable region or the writable region based on a result of the comparison.
12. The method as claimed in claim 11 , wherein step (1) includes a step of detecting a read channel 1 signal being a summation of optical signals reflected from the optical recording medium.
13. The method as claimed in claim 12 , wherein step (2) compares the detected signal with a reference value, thereby to determine a region as the non-writable region based on a result of the comparison.
14. The method as claimed in claim 11 , further comprising:
(4) holding a servo error signal for a servo control if a point of the optical recording medium being written or read at the present time is determined to be a non-writable region.
15. The method as claimed in claim 11 , further comprising:
(4) counting a number of the determined non-writable regions, to determine the present track of being a land track or a groove track, and
(5) performing a land/groove switching operation depending on a result of the determination.
16. The method as claimed in claim 11 , wherein step (1) includes a step of obtaining at least a bottom hold signal from the summed signal.
17. The method as claimed in claim 16 , wherein step (3) determines the present region as the non-writable region or the writable region as comparing the bottom held value with the reference value.
18. The method as claimed in claim 17 , wherein step (3) determines the present region as the non-writable region if the bottom held value is greater than the reference value, and as the writable region if the bottom held value is smaller than the reference value.
19. A method for detecting a non-writable region of an optical recording medium, the method comprising the steps of:
detecting a non-writable region of an optical recording medium, by comparing a read channel 1 or a read channel 2 signal with a reference value, the read channel 2 signal being a difference of optical signals reflected from the optical recording medium, and the read channel 1 signal being a summation of optical signals reflected from the optical recording medium; and
controlling a read or write operation based on the result of the detection step.
20. The method as claimed in claim 19 , further comprising the step of changing the reference value be to compared with a read channel 1 or a read channel 2 signal, thereby to detect a non-writable region of an optical recording medium.
21. The method as claimed in claim 20 , further comprising the step of determining a region as the non-writable region if a low pass filtered value is greater than the changed reference value.